A report in the July issue of the Journal of Clinical Investigation revealed that a group of drugs currently under development for the treatment of Type II diabetes causes both increased heart rate and elevated blood pressure in animal studies.

These new findings regarding the category of drug known as a glucagon-like peptide (GLP-1) receptor agonist suggest that the brain's GLP-1 system has the ability to affect autonomic function, leading to changes in heart rate and blood pressure.

A naturally occurring hormone that is produced by cells lining the intestine, GLP-1 was first targeted as a diabetes treatment about 15 years ago, according to the study's senior author Joel Elmquist, D.V.M., Ph.D., a neuroscientist and endocrinologist at Beth Israel Deaconess Medical Center and Associate Professor of Neurology and Medicine at Harvard Medical School.

"GLP-1 stimulates insulin secretion and controls feeding and drinking behavior, and also regulates neuroendocrine responses to agents that elicit illness-like behaviors," he explained. "The effect on insulin secretion made the hormone an obvious target for treating diabetes."

Diabetes develops when the body fails to either produce or to properly use insulin, a hormone necessary to convert food — including sugars and starches — into energy. Type II diabetes accounts for the majority of cases of the disease, and is a huge public health problem. As many as 16 million individuals in the United States have Type II diabetes, which puts them at risk for a number of serious complications, including stroke and heart disease.

Although diabetes can often be controlled through diet and exercise, pharmaceutical companies continue to develop medications that can be used to manage the disease. However, as this latest study shows, scientists do not yet understand enough about the functioning of the human brain and body to ensure that these drugs are effective — or safe.

"Despite accumulating data linking GLP-1 to autonomic and neuroendocrine responses, the pathways [responsible] for the actions were previously not well understood," explained Elmquist. "Although these new findings in animals will need to be studied further, especially in diabetic models, this research suggests that the central GLP-1 system can regulate sympathetic outflow including raising heart rate and blood pressure."